[1] Others with larger effusions may present with chest pressure or pain, dyspnea, shortness of breath, and malaise (a general feeling of discomfort or illness).

Yet others with cardiac tamponade, a life-threatening complication, may present with dyspnea, low blood pressure, weakness, restlessness, hyperventilation (rapid breathing), discomfort with lying flat, dizziness, syncope or even loss of consciousness.

Some examples are nausea and abdominal fullness, dysphagia and hiccups, due to compression of stomach, esophagus, and phrenic nerve respectively.

[citation needed] A pericardial effusion with enough pressure to adversely affect heart function is called cardiac tamponade.

[2] Patients with pericardial effusion may have unremarkable physical exams but often present with tachycardia, distant heart sounds and tachypnea.

[5] A physical finding specific to pericardial effusion is dullness to percussion, bronchial breath sounds and egophony over the inferior angle of the left scapula.

[2] Patients with concern for cardiac tamponade may present with abnormal vitals and what's classically known as the Beck's triad, which consists of hypotension (low blood pressure), jugular venous distension and distant heart sounds.

In cardiac tamponade, the pressure within the pericardium is significantly higher, hence decreasing the compliance of the chambers (the capacity to expand/ conform to volume changes).

[2] Some patients with pericardial effusions may present with no symptoms and the diagnosis can be an incidental finding due to imaging of other illnesses.

Patients who present with dyspnea or chest pain have a broad differential diagnosis and it may be necessary to rule out other causes like myocardial infarction, pulmonary embolism, pneumothorax, acute pericarditis, pneumonia, and esophageal rupture.

Electrical alternans signifies the up-and-down change of the QRS amplitude with every beat due to the heart swinging in the fluid (as displayed in the ultrasound image in the introduction) .

[citation needed] Echocardiogram (ultrasound): when pericardial effusion is suspected, echocardiography usually confirms the diagnosis and allows assessment of the size, location and signs of hemodynamic instability.

Although it's difficult to define size classifications because they vary with institutions, most commonly they are as follows: small <10, moderate 10–20, large >20.

[5] An echocardiogram is urgently needed for evaluation when there is concern for hemodynamic compromise, a rapidly developing effusion or history of recent cardiac surgery/procedures.

[5] After the procedure, the aspirated fluid is analyzed for gross appearance (color, consistency, bloody), cell count, and concentration of glucose, protein, and other cellular components (for example lactate dehydrogenase).

In case of malignant effusions, the high likelihood of recurrence of fluid accumulation is the main reason for a surgical procedure.